TOPLINE:
Attention-deficit/hyperactivity disorder (ADHD) and comorbid psychiatric disorders are associated with a twofold increased risk for schizophrenia, new research shows.
METHODOLOGY:
- Investigators analyzed the data of 211,705 people aged 5-19 years (74% male; 54% aged 5-9 years) diagnosed with ADHD during 2010-2018 from the Health Insurance Review and Assessment Service database of South Korea.
- Participants with a diagnosis of schizophrenia or psychosis anytime in the 3 years prior to ADHD diagnosis were excluded.
- Investigators split participants into two groups — a group of those diagnosed with at least one psychiatric comorbidity within a year of ADHD diagnosis and another group comprising those with ADHD and no psychiatric comorbidities.
TAKEAWAY:
- 37% (77,890) of those with ADHD had at least one comorbid psychiatric disorder.
- Participants with one psychiatric comorbidity had a 2.1-fold increased risk for a schizophrenia diagnosis than participants with no comorbidity (adjusted hazard ratio [aHR], 2.14; 95% CI, 2.05-2.23).
- Schizophrenia risk increased with each additional comorbidity. There was a fourfold increased risk for schizophrenia in study participants with three or more psychiatric comorbidities (aHR, 4.26; 95% CI, 3.90-4.65) than those with no comorbidity.
- Psychiatric comorbidities included autism spectrum disorder, which had the strongest link to increased schizophrenia risk (aHR, 2.43; 95% CI, 2.26-2.62). Other comorbidities that showed strong associations were intellectual disability (aHR, 1.83; 95% CI, 1.72-1.95), tic disorder (aHR, 1.77; 95% CI, 1.66-1.88), depression (aHR,1.68; 95% CI, 1.60-1.77), and bipolar disorder (aHR, 1.67; 95% CI, 1.53-1.83).
IN PRACTICE:
“To our knowledge, this is the first study to investigate schizophrenia risk among children and adolescents with ADHD, with a particular focus on psychiatric comorbidities,” the researchers wrote. They also noted that although patients had no psychiatric comorbidities at the time of ADHD diagnosis, the occurrence of psychiatric comorbidities was frequently observed prior to schizophrenia diagnosis.
“These findings highlighted the significance of carefully monitoring psychiatric comorbidities in patients with ADHD to effectively mitigate the burden of schizophrenia,” they noted.
SOURCE:
Soo Min Jeon, PharmD, PhD, of Jeju National University in Jeju, South Korea, led the study, which was published online on November 30, 2023 in JAMA Network Open.
LIMITATIONS:
Since the diagnosis of ADHD, schizophrenia, and other psychiatric comorbidities were based on diagnostic codes, the possibility of underdiagnosis or overdiagnosis cannot be ruled out. Also, some patients with ADHD chose the general health consultation (International Classification of Diseases - Z code) due to the social stigma surrounding mental health problems.
DISCLOSURES:
The study was funded by the Basic Science Research Program through the Ministry of Education and the Health Insurance Review and Assessment Service. Author disclosures can be found in the original paper.
A version of this article appeared on Medscape.com.